1. Field of the Invention
This invention relates to an apparatus and a process for producing coatings on multi-width sheets or webs using wet or dry materials in the coating process. More particularly, the invention relates to a rotatable coating hopper for depositing coating materials on sheets or webs for producing roofing sheets or shingles.
2. Reported Developments
It is well known in the prior art in the field of building materials to coat roofing sheets and shingles for protection against the elements and/or for rendering a pleasing appearance to such sheets and shingles. Typically, the coating comprises asphalt and a granular or powder material which is deposited on the molten asphalt. When the asphalt cools, the granular or powder material becomes embedded therein. Various apparata and processes are used to produce the coated sheets or shingles illustrative of which are the following.
U.S. Pat. No. 3,730,397 discloses a granules applicator for applying granular material to sheets of roofing material.
The granular applicator unit comprises a granule hopper which is located well above a horizontal path along which a sheet moves continuously during the application of the granules. A cavity roll, having one cavity, is located directly under the hopper and drives a belt that is carried by idler rolls. There are three idler rolls which hold the belt against the cavity roll. A distribution roll is located under the third idler roll and directly above the moving sheet. A deflector gate, associated with the distribution roll, provides a distribution gate for the granules which fall onto the sheet in a uniform layer. The pattern of distribution is limited to one single pattern since the cavity roll has only one cavity therein.
In order to vary the pattern of the granules applied, the patentee suggests using a number of such units to be used in tandem. However, even if several of these units were used in tandem, the pattern that could be created would run only laterally to the longitudinal direction of the sheet of roofing material.
U.S. Pat. No. 4,356,216 discloses a process for producing striped surface coatings such as used to create a pattern simulating the appearance of natural wood grain. The process includes the following steps.
A first liquid coating material, such as a paint, is applied to a strip surface; then a second coating material is delivered through one or more apertures onto the painted strip surface. The apertures are provided in a rotatable disk. Rotary movement of the disk angularly displaces the apertures so as to vary the location and spacing of the produced stripes.
U.S. Pat. No. 4,583,486 discloses an apparatus for depositing granules on a moving sheet. The apparatus is positioned above a moving sheet which travels laterally to the apparatus. The apparatus comprises:
a hopper having an open area at its bottom portion is designed to receive granules;
a perforated belt adapted to close the open area in the bottom portion of the hopper; and
motor means to drive the belt in one direction only; whereby granules received by the hopper drop through the perforations in the belt and are deposited on the moving sheet.
By changing the angle between the moving sheet and the perforated belt and adjusting their speed of travel the pattern of deposition may be varied.
U.S. Pat. No. 5,382,291 discloses an apparatus for making decorations on tarred membranes for surface covering in the construction industry.
The apparatus comprises:
a hopper which contains solid particles in the form of scales, sands or granules; and
an applicator for applying the solid particles in a decorative pattern.
The applicator is positioned below the hopper and includes a rotating roller, or a rotating ring-wound continuous belt or a rotatable plate each of which have a replaceable skin covering the same, the skin having cut-ins of the decorative pattern intended to be transferred onto a tarred surface.
The process of producing decorative pattern on a tarred surface is as follows. First, a membrane intended for use in the building industry is tarred in an impregnation bath which contains the hot tar. The tarred membrane travels on a continuous belt toward the applicator which is fed from the hopper containing the solid particles. The solid particles fall, by gravity, onto the rotating roller, or on a ring-wound continuous belt, or on a rotatable plate each of which has the desired decorative pattern. By rotation, the solid particles are dumped onto the tarred membrane on which they assume the same pattern as they had on the rotating roller. Subsequently, the tarred membrane with the decorative pattern thereon is dried and packaged.
If desired, a layer of grit may be deposited on the tarred and decorated membrane prior to the drying step. The deposition of grit is accomplished by an applicator similar to that used to deposit the pattern, but without the rotating roller having any design cut into the skin covering the rotating roller.
U.S. Pat. No. 5,534,114 discloses a method and apparatus for applying a fluid material to a web.
The apparatus for applying a fluid material to a substrate comprises:
means for moving a substrate along a first path;
means for moving an orifice along a second endless path, the orifice crossing the first path; and
a housing assembly comprising:
means for retaining a supply of fluid material alone in the second path portion and under pressure; and
means for communicating the retained supply of fluid material under pressure with the orifice which it moves along the second path as the fluid material is discharged continuously and transversely upon the substrate.
The bands produced by the apparatus can be perpendicular to web travel; the width of the bands can be increased by increasing the slurry supply; and the angle of the bands can be changed by altering the pivot of the moving orifice applicator.
The prior art devices and processes do not a dequately provide for the production of multi-width products and coatings; and for production of patterns that can be in the machine direction, or perpendicular to machine direction, or any angle between machine direction and perpendicular to the machine direction.
The present invention is directed to solve these shortcomings of the prior art.
In accordance with the present invention there is provided an apparatus and a process for coating a continuously advancing web with a dry or a wet coating material.
The apparatus comprises: a carousel, or turn table, rotatable from 0xc2x0 to 90xc2x0 angles around its vertical center axis; an applicator having an applicator port therein for discharging the coating material to the web; and a hopper positioned over and associated with the carousel and rotatable therewith for the containment and delivery of the coating material to the applicator. The apparatus is positioned over a continuously advancing conveyor belt which carries the web in a longitudinal direction. The applicator through its discharge port deposits the coating material in the form of stripes, bars or a uniform layer onto the web forming a coating thereon.
The hopper preferably contains three rotating devices, e.g., rolls, therein for sifting the coating material and delivering it to the applicator: an agitator in the upper portion of the hopper for stirring the coating material and maintaining it in a fluid, uncoagulated condition; a brush positioned downward from the agitator for receiving the coating material from the agitator; and a knurled roll which contacts and rubs against the brush and carries the coating material out of the applicator. The brush contains bristles between which the coating material is dispersed. The bristles bend when rubbing against the knurled roll resulting in the release of the coating material.
The apparatus also includes feeding chutes positioned over the hopper for continuous delivery of the coating material into the hopper.
In accordance with the present invention, a process for producing coatings on a continuously advancing web designed for shingles and sheets used in the building materials industry is also provided. The web is typically pre-coated with a hot-melt material, such as asphalt, prior to being subjected to the coating process of the present invention. Pre-coating is accomplished in a hot bath containing the hot melt material and is well-known in the prior art. Such pre-coating is preferable when dry coating materials, such as granules, are used so as to imbed the granules in the hot melt coated web. The pre-coated web is then coated by the process of the present invention comprising the steps of: feeding the hopper with the desired coating material; allowing the coating material to pass through the discharge port and be deposited on the continuously advancing web to form stripes, bars or a uniform layer thereon. The separation or width of the stripes, bars or uniform layer can be varied by rotating the carousel between 0xc2x0 and 90xc2x0.